I have some issue with my feet and knees, but still want to do cardio. Are there some low impact high calorie workouts easy on both of these?

As in, ones that require no or little equipment? I was thinking yoga because I heard that can work up a sweat, or maybe some random tae-bo type thing, but I wanted to hear what you thought as all I'm finding online are ones designed for grandma.

One quick addendum: although I said "no equipment" I do have weights lying around that I'm using for strength-training 3-4x a week, basically my schedule each day is:

Morning: Cardio
Night: Weights

I would be willing to use the weights/bands for cardio but I know you're supposed to rest your muscles, so not sure if I could use them somehow without effecting the growth of my muscles.